Beneficiation of ores



United States Patent BENEFICIATION OF ORES David S. Breslow, Wilmington, Del., assignor to Hercules lrsozvder Company, Wilmington, Del., a corporation of e aware No Drawing. Application May 18, 1955, Serial No. 509,382

6 Claims. (Cl. 209-166) The present invention relates to a process for beneficiating ores and more particularly to a process for concentrating ores by froth flotation.

Reagents used in the flotation of ores are of three general types, namely, frothing agents, collecting agents and modifying agents. Frothing agents depress the surface tension of the water employed and thus facilitate the formation of air bubbles when the water is aerated. Collectors serve to modify the surfaces of the ore particles and cause them to adhere to the air bubbles which are formed in the water. Modifying agents are used to modify the ore pulp so that the desired minerals will be collected in the froth and the remainder will not. The action of modifying agents is thus supplementary to that of the collectors.

Frothers heretofore employed in the flotation of minerals include pine oil, cresylic acid, creosotes, aliphatic alcohols, soaps and, in a few instances, sulfonated organic compounds. The efliciency of these frothing agents vary from ore to ore so that in the case of a particular ore one frothing agent may be more eificient than another. It is desirable, of course, that a frothing agent be as eflicient as possible and also that it be versatile as to the type of ore on which it is efiective.

It has now been discovered that 4-(tetrahydro-2- furyl)-2-butanol and 1,5-di(tetrahydro-Z-furyl)-3-pentan- 01 are both eificient and versatile frothing agents in accordance with this discovery the present invention provides a method of concentrating ores which is characterized by the step of subjecting to froth flotation an aqueous pulp of the ore in the presence of a collector and a frothing agent selected from the group consisting of 4-(tetrahydro-2-furyl)-2-butanol and 1,5-di(tetrahydro-2-furyl)- 3-pentanol.

Having indicated in a general way the nature and purpose of the invention, the following examples are offered as illustrative embodiments. All parts and percentages are by weight unless otherwise indicated.

EXAMPLE 1 The ore concentrated in this example was a copper sulfide ore containing about 0.9% copper, chiefly in the form of chalcopyrite, pyrite in greater abundance than the copper mineral, and a gangue of siliceous minerals. In the beneficiation procedure, 505 parts of the ore, 500 parts of water and 1.5 lb. lime per ton of ore were ground in a ball mill for 14 minutes. The ground ore was then screened through a 48 mesh screen and the undersize transferred to a Denver flotation machine. The pulp was diluted to about 20% solids with water and then 0.016 lb. KCN per ton of ore and 0.04 lb. potassium amyl xanthate per ton of ore were added and the ore conditioned for 1 minute.

A frothing agent (as specified in the following table) was then added, the ore conditioned 1 minute and a copper concentrate was removed for 7 minutes. The con- 2,767,842 Patented Oct. 23, 1956 Fee centrate was examined for flocculation. results of the tests are as follows:

Table I FROTHER TESTS ON COPPER SULFIDE ORE The complete Concen Telling, Test Frother Lb./ton trate, Percent Percent Cu 1 'i s y ni iii i 1 1 h 1 e amy a co 0 Cresy acid 0. 29 5.0 0.087 2 Same 0.22 3.4 0.099

0.29 5.4 0.077 0. 19 4. 8 0. 077 6 Same 0.10 3.6 0.13 7 of 4-(Tetrahydro-2-turyl)- 2-butanol+25% cresylic acid. 0. 22 5. 6 0. 076

It is evident from the data that the frothing agent employed in the example is even more eflicient than the standard frothing agent, a mixture of 75% methyl amyl alcohol and 25% cresylic acid.

EXAMPLE 2 The ore beneficiated in this example was a zinc ore analyzing about 9.3% sphalerite. Pyrite and siliceous gangue minerals were also present. The standard frothing agent was pine oil. In the beneficiation procedure, 5.0 parts of ore and 500 parts of water was charged to a ball mill and ground for 9 minutes. The ground ore was then screened through a 48-mesh screen and the undersize transferred to a Denver flotation machine where it was diluted with water to about 20% solids and conditioned for 10 minutes with 2 lb. lime per ton of ore, 1.4 lb. copper sulfate per ton of ore,- and 0.04 lb. KCN per ton of ore. Next, 0.10 lb. potassium amyl xanthate per ton of ore was added followed immediately by the addition of frothing agent. A zinc concentrate was removed for 10 minutes. The data are as follows:

Table II FLOTATION TESTS ON ZINC ORE Coneen- Telling, Test Reagent Lb./ton trate, Percent (Frother) Percent Zn l Pine Oil 0.18 17. 5 0. 51 2 1-(Tetrahydro-2-turyD-2- butanol 0. 19 19. 0 0. 44

It is obvious from the above data that the exemplified process of the invention is even more eflicient than the standard process which utilizes pine oil.

EXAMPLE 3 The procedure of Example 1 was followed using 1,5- di(tetrahydro-2-furyl)-3-pentanol as the frothing agent. The results obtained are as folows:

3 EXAMPLE 4 The procedure of Example 2 was followed using 1,5- di(tetrahydro-2-furyl)-3-pentanol as the frothing agent in the amount of 0.20 lb. per ton of ore. The percent weight of concentrate was 17% and the percent zinc in the tailing was 0.73%.

Examples 3 and 4 show that l,5-di(tetrahydro-2- furyl)-3-pentanol is a highly eflicient frothing agent although 4-(tetrahydro2-furyl)-2-butanol is preferred because of its even greater efficiency.

In the beneficiation of minerals by the froth flotation process, the ore or mineral to be concentrated is first finely ground in the presence of water to the proper particle size for the purpose of liberating the gangue from the metalliferous or mineral components. The ground material is screened to remove the oversized particles. The resultant pulp may then be treated in any of the various types of aerating machine which have been developed for the purpose. Thus, vortex, superaeration, and pneumatic machines of the air-jet type may be employed. customarily, the value mineral; i. e., the product product which it is desired to recover, is floated. However, the procedure may be reversed with the value mineral concentrated in the tailing and the gangue removed in the froth.

Bulk flotation involves the flotation from the ore of a single rough concentrate containing a group of valuable minerals of the ore. Divisional flotation involves a more refined separation of minerals of similar flotation properties from each other, giving a product or number of products each of which contains, in so far as possible, one mineral or only minerals whose presence together is commercially desirable.

The frothing agents of this invention are, of course, operable in both bulk and divisional flotation procedures involving any mineral or ore. Furthermore, these frothing agents are equally advantageous when employed in any of the various types of machines adapted to the processes involved.

The frothing agents of this invention may be utilized in amounts of from about 0.005 lb. to about 1 lb./ton of ore but are preferably employed in amounts of from about 0.01 lb. to about 0.5 lb./ton of ore. In most instances, it is advantageous to employ other flotation agents in addition to the frothers to achieve the most effective separation of the minerals from the ore. These additional froth flotation reagents include collectors and modifying agents.

Collecting agents are chemical compounds which cause the collection of the desired material into the froth. The compounds most commonly employed with metallic sulfide and oxidized metallic ores are the xanthates, dithiophosphates and diphenyl thiourea. Potassium or sodium ethyl, butyl, and amyl xanthates or mixtures of these are also widely used. The collectors known as dithiophosphates are prepared by the reaction of phosphorus pentasulfide with alcohols or phenols. The most utilized of such compounds are the phosphocresylic acids which contain various percentages of cresylic acidadded in excess during the manufacturing process. Sodium salts of these phosphocresylic acids are also valuable collectors. Likewise, useful collecting agents may be prepared from phosphorus pentasulfide and ethyl, amyl, or butyl alcohols.

In the flotation of nonmetallic ores, fatty acids, fatty acid soaps, and derivatives thereof are most commonly employed as collectors. Typical fatty acids utilized are oleic, stearic, and palmitic. Likewise, soaps comprising the alkali metal salts of these acids are excellent collectors. Sulfonated fatty acids and fatty acid soaps are also widely employed in the art as collecting agents and have the advantage of being more selective in their action. Other comparably effective collectors for ores are those amines derived from a rosin or a modified IOSlIl, such as hydrogenated rosin, polymerized rosin, he 108m,

isomerized rosin, or the like, and the water-soluble salts of these amines. The amines may be prepared either from the rosin materials or from the pure acids contained therein, such as abietic acid, dehydroabietic acid, dihydroabietic acid, tetrahydroabietic acid and the like. The amine derived from dehydroabietic acid, for example, is dehydroabietylamine.

The frothing agents of this invention may be efficaciously and advantageously utilized with any of the various collecting agents hereinbefore mentioned. Furthermore, they are also operable with other collecting agents known to the art.

Modifying agents are of various types and include pH and pulp control agents, depressing agents, activating agents, sulfidizing agents, dispersing agents, and inhibitors.

The most commonly employed pH and pulp control agents are lime and soda ash for alkaline circuits and sulfuric acid for acid circuits.

Depressing agents include lime, sodium and potassium cyanide, sodium sulfate, sodium sulfite, sodium sulfide, sulfur dioxide, and potassium and sodium dichromate. These compounds are employed both independently and in various combinations.

Copper sulfate, sodium sulfide, and sulfuric acids are used as activating agents for metallic ores. Soluble basic salts of copper, lead and iron are so utilized in the soap flotation of nonmetallic ores and, as sulfidizing agents, sodium sulfide, hydrogen sulfide, and the various other sulfides and polysulfides of the alkali and alkaline earth metals are employed. Dispersing agents commonly utilized are sodium silicate, sodium sulfide, citric acid, tannic acid, and lactic acid. Protective colloids, such as starch, glue, gum arabic, casein, gelatin and the like, are excellent inhibitors.

One skilled in the art of ore beneficiating by froth flotation will be cognizant of the proper collecting and modifying agents to employ to obtain the optimum results from the flotation of a particular ore. The frothing agents of this invention may be utilized in conjunction with any of the modifying and collecting agents hereinbefore mentioned, either alone or in combination. It is to be understood, however, that they are also operable with various other flotation reagents, including frothers, known to the art.

The frothing agents of this invention may be used generally in the dressing of ores. Sulfide ores, nonsulfide ores, both simple and complex and nometallic ores may be advantageously so treated. Thus, lead, zinc, copper, iron, molybdenum, nickel and precious metal sulfide and nonsulfide ores may be economically concentrated by froth flotation according to the invention. Likewise, mineral ores, such as coal ores, are most eflicaciously beneficiated in the presence of the froth flotation reagent disclosed.

The process is generally operable for the conditioning or ores or the treating of minerals. However, the conditions most desirable for frothing operations are dependent, in addition to the froth flotation agent, on the size of the ore being treated, the temperature at which the treatment is carried out, the per cent solids in the pulp, and the pH of the flotation mixture. In each case, one skilled in the art will be able to adjust the various conditions to achieve the optimum advantages from the flotation agent employed.

The physical properties of the froth produced are excellent. The froths are composed of fine bubbles which adequately support the weight of the floated mineral. thus facilitating its removal. Furthermore, the froths do not demonstrate undue stiffness or brittleness but collapse rapidly and completely after the concentrate has been removed. In addition, the froths produced are clean with respect to the fine, slimy gangue which has a tendency to float and contaminate the metallic concentrate.

The frothing agents employed in the invention are known compounds which can be prepared according to known procedures. For instance, 4-(tetrahydro-2-furyl)- Z-butanol can be prepared by hydrogenating furfural acetone (monofurylidene acetone) in solution in ethanol at 150 C. and under hydrogen pressure of 2000 p. s. i. The pure alcohol was recovered by fractional distillation under vacuum as a fraction boiling at 9094 C. at 5 mm. pressure. In a similar manner, 1,5-di-(tetrahydro- 2-furyl)-3-pentanol can be prepared by hydrogenation of difurfural acetone (difurylidene acetone).

What I claim and desire to protect by Letters Patent is:

1. In the beneficiation of ores, the step which comprises subjecting an aqueous pulp of an ore to froth flotation in the presence of a collector and a frothing agent selected from the group consisting of 4-(tetrahydro-2-furyl)-2-butanol and 1,5-di-(tetrahydro-Z-furyl)-3- pentanol.

2. The process of claim 1 wherein the amount of frothing agent ranges from 0.005 to 1 lb. per ton of ore.

3. The process of claim 1 in which the ore is a zinc sulfide ore.

4. The process of claim 1 in which the ore is a copper sulfide ore.

5. The process of claim 1 in which the frothing agent is 4- tetrahydro-Z-furyl) '2-butano1.

6. The process of claim 1 in which the frothing agent is l,5-di(tetrahydro-2furyl)-3-pentan0l.

No references cited. 

1. IN THE BENEFICIATION OF ORES, THE STEP WHICH COMPRISES SUBJECTING AN AQUEOUS PULP OF AN ORE TO FROTH FLOTATION IN THE PRESENCE OF A COLLECTOR AND A FROTHING AGENT SELECTED FROM THE GROUP CONSISTING OF 4-(TETRAHYDRO-2-FURYL)-2-BUTANOL AND 1,5-DI-(TETRAHYDRO-2-FURYL)-3PENTANOL. 